Apparatus and method for converting color signal, and computer-readable recording medium for storing computer program for controlling the apparatus

ABSTRACT

An apparatus and a method for converting a color signal and a computer-readable recording medium storing a computer program for controlling the apparatus. The apparatus converts an input color signal including first through m th  input color components into an output color signal including first through n th  (n&gt;m) output color components. The apparatus includes: a combination extractor which extracts combinations for the first through n th  output color components; a coefficient generator which generates a coefficient for representing the input color signal using the input color signal and the extracted combinations; a combination selector which selects desired combinations among the extracted combinations using the coefficient; and an output unit which generates the output color signal using the selected combinations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No.2004-0057542, filed on Jul. 23, 2004, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of image processing fordisplaying an image in a multi-primary color, and more particularly, toan apparatus and a method for converting an input color signal having mcolor components into an output color signal having n (>m) output colorcomponents, and a computer-readable recording medium for storing acomputer program for controlling the apparatus.

2. Description of Related Art

One of several conventional multi-primary color converting methods isdisclosed in U.S. Pat. No. 6,633,302 assigned to Olympus Optical Co.,Ltd. When that disclosed multi-primary color converting method isapplied to a system of more than five primary colors, the division of acolor space becomes very complicated. Also, when neighboring colors aredistributed into different selection areas, the boundaries among theneighboring colors are prominent.

Another conventional multi-primary color converting method is disclosedin International Patent No. WO 01/099557 assigned to Genoa ColorTechnologies, Ltd. In that disclosed multi-primary color convertingmethod, a complicated process of computing a lookup table (LUT) isrequired.

In addition, a maximum saturation value and a maximum luminance value animage display device can represent vary depending on the type of usedconventional multi-primary color converting methods. As a result, thequality of an output image is deteriorated.

BRIEF SUMMARY

An aspect of the present invention provides an apparatus and a methodfor converting an input color signal having m color components into anoutput color signal having n (>m) color components while fullyrepresenting a color gamut of an output display device.

An aspect of the present invention also provides a computer-readablerecording medium for storing a computer program for controlling theapparatus.

According to an aspect of the present invention, there is provided anapparatus for converting an input color signal including first throughm^(th) input color components into an output color signal includingfirst through n^(th) (n>m) output color components. The apparatusincludes: a combination extractor which extracts combinations of thefirst through n^(th) output color components; a coefficient generatorwhich generates a coefficient for representing the input color signalusing the input color signal and the extracted combinations; acombination selector which selects desired combinations among theextracted combinations using the coefficient; and an output unit whichgenerates the output color signal using the selected combinations.

According to another aspect of the present invention, there is provideda method of converting an input color signal including first throughm^(th) input color components into an output color signal includingfirst through n^(th) (n>m) output color components. The method includes:extracting combinations of the first through n^(th) output colorcomponents; generating a coefficient for representing the input colorsignal using the input color signal and the extracted combinations;selecting desired combinations among the extracted combinations usingthe coefficient; and generating the output color signal using theselected combinations.

According to still another aspect of the present invention, there isprovided a computer-readable recording medium for storing a computerprogram for controlling an apparatus for converting an input colorsignal including first through m^(th) input color components into anoutput color signal including first through n^(th) (n>m) output colorcomponents. The computer program includes: extracting combinations ofthe first through n^(th) output color components; generating acoefficient for representing the input color signal using the inputcolor signal and the extracted combinations; selecting desiredcombinations among the extracted combinations using the coefficient; andgenerating the output color signal using the selected combinations.

Additional and/or other aspects and advantages of the present inventionwill be set forth in part in the description which follows and, in part,will be obvious from the description, or may be learned by practice ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages of the present inventionwill become apparent and more readily appreciated from the followingdetailed description, taken in conjunction with the accompanyingdrawings of which:

FIG. 1 is a block diagram of an apparatus for converting a color signal,according to an embodiment of the present invention;

FIG. 2 is a flowchart for explaining a method of converting a colorsignal, according to an embodiment of the present invention;

FIG. 3 is a view for illustrating an example of a polyhedron representedon an intermediate color space;

FIG. 4 is a block diagram of an example of the combination extractor ofFIG. 1;

FIG. 5 is a block diagram of another example of the combinationextractor of FIG. 1;

FIG. 6 is a block diagram of an example of the coefficient generator ofFIG. 1;

FIG. 7 is a block diagram of an example of the combination selector ofFIG. 1;

FIG. 8 is a block diagram of an example of the output unit of FIG. 1;

FIG. 9 is a block diagram of another example of the output unit of FIG.1; and

FIG. 10 is a block diagram of still another example of the output unitof FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

FIG. 1 is a block diagram of an apparatus for converting a color signal,according to an embodiment of the present invention. Referring to FIG.1, the apparatus includes a combination extractor 10, a coefficientgenerator 12, a combination selector 14, an output unit 16, and a colorcomponent converter 18.

FIG. 2 is a flowchart for explaining a method of converting a colorsignal, according to an embodiment of the present invention. Here, themethod includes operations 30, 32, and 34 of obtaining desiredcombinations of output color components and operation 36 of generatingan output color signal. The method of FIG. 2 may be performed by theapparatus of FIG. 1. Thus, for ease of explanation only, the method ofFIG. 2 and the apparatus of FIG. 1 are described in conjunction witheach other. However, it is to be understood that the method of FIG. 2can be performed by apparatuses of other configurations and that theapparatus of FIG. 1 can perform other methods.

The apparatus of the present embodiment converts an input color signalhaving first through m^(th) input color components into an output colorsignal having first through n^(th) output color components. Here, n islarger than m.

In operation 30, the combination extractor 10 of FIG. 1 extractscombinations 13 of first through n^(th) output color components inputvia an input node IN1 and outputs the extracted combinations 13 to eachof the combination selector 14 and the coefficient generator 12. Inother words, the combination extractor 10 divides an output color spaceto which the first through n^(th) output color components belong andextracts possible candidate combinations from the divided output colorspace.

FIG. 3 is a view for illustrating an example of a polyhedron representedon an intermediate color space.

The combination extractor 10 of FIG. 1 may convert the extractedcombinations 13 into position vectors and output the position vectors.Here, the position vectors include position components for indicatingpositions of points belonging to an internal space of a polyhedronrepresented on an intermediate color space and bias components of thepolyhedron. Here, the intermediate color space refers to a color spacewhich mediates between an input color space and an output color spaceand includes coordinate axes of more than three dimensions. In otherwords, an arbitrary point on the input color space may be matched with apoint on the intermediate color space, and an arbitrary point on theoutput color space may be matched with a point on the intermediate colorspace. Also, the bias components of the polyhedron refer to distancecomponents between vertexes of the polyhedron on the intermediate colorspace and a reference point on the intermediate color space.

For example, the polyhedron may be a hexahedron 50 as shown in FIG. 3,and the intermediate color space may be an LAB color space. Here, theposition components may be P_(i), P_(j), and P_(k), and in a case ofFIG. 3, a bias component may be a distance component P_(k2) between areference point RP on the intermediate color space and a vertex 52 ofthe hexahedron 50.

FIG. 4 is a block diagram of an example 10A of the combination extractor10 of FIG. 1, including a combiner 70, a component generator 72, and aposition vector generator 74.

The combiner 70 of FIG. 4 extracts possible combinations of a specifiednumber of output color components from the first through n^(th) outputcolor components input via an input node IN3 and outputs the extractedcombinations to each of the component generator 72 and the positionvector generator 74. Here, the specified number is less than a number ofcoordinate axes of the polyhedron and as few as a number of biascomponents of the polyhedron. As shown in FIG. 3, in a case where anumber of coordinate axes for describing coordinates of an arbitrarypoint belonging to an internal space of the hexahedron 50 is 3, and onlythe bias component P_(k2) exists, the specified number is 2, and acombination of P_(i) and P_(j) is extracted. Here, a number of extractedcombinations can be represented as in Equation 1:

$\begin{matrix}{n_{c} =_{\;}{{{}_{}^{}{}_{}^{}} = \frac{n!}{{\left( {n - Q} \right)!} \times {Q!}}}} & (1)\end{matrix}$wherein n_(c) denotes the number of extracted combinations, and Qdenotes the specified number.

For example, when n=5, first through fifth output color components arered (R), green (G), blue (B), cyan (C), and yellow (Y), and thespecified number is 2 as shown in FIG. 3, ten types of combination ofP_(i) and P_(j). i.e., RG, RB, RC, RY, GB, GC, GY, BC, BY, and CY areextracted.

The component generator 72 generates a position component including abias component among the position components using the first throughn^(th) output color components input via the input node IN3 and thecombinations input from the combiner 70 and outputs the positioncomponent to the position vector generator 74. Here, the componentgenerator 72 outputs a bias component 15 to each of the coefficientgenerator 12 and the output unit 16 via an output node OUT2.

For example, as shown in FIG. 3, the component generator 72 generatesthe position component P_(k) including the bias component P_(k2) amongthe position components P_(i), P_(j), and P_(k). Here, as shown in FIG.3, the position component P_(k) can be represented as in Equation 2:P _(k) =P _(k1) −P _(k2)  (2)wherein bias components P_(k1) and P_(k2) can be represented as inEquation 3:

$\begin{matrix}{{P_{k\; 1} = {\sum\limits_{s = 1}^{n}\left( {\sigma_{s}^{1} \cdot P_{s}} \right)}}{P_{k\; 2} = {\sum\limits_{s = 1}^{n}\left( {\sigma_{s}^{2} \cdot P_{s}} \right)}}} & (3)\end{matrix}$wherein P_(s) denotes each of the first through n^(th) output colorcomponents, and σ_(S) ¹ and σ_(s) ² can be represented as in Equations 4and 5, respectively:

$\begin{matrix}{\sigma_{s}^{1} = \begin{Bmatrix}{{1\mspace{14mu} s} \in \left\{ {{s\text{|}{P_{s} \cdot \left( {P_{i} \times P_{j}} \right)}} < 0} \right\}} \\{0\mspace{14mu}{otherwise}}\end{Bmatrix}} & (4) \\{\sigma_{s}^{1} = \begin{Bmatrix}{{1\mspace{14mu} s} \in \left\{ {{s\text{|}{P_{s} \cdot \left( {P_{i} \times P_{j}} \right)}} > 0} \right\}} \\{0\mspace{14mu}{otherwise}}\end{Bmatrix}} & (5)\end{matrix}$

The position vector generator 74 generates a position vector using thecombinations extracted by the combiner 70 and the position componentgenerated by the component generator 72 and outputs the position vector13 to each of the combination selector 14 and the coefficient generator12 via an output node OUT3. In a case of FIG. 3, a position vectorM_(cubic) can be represented as in Equation 6:

$\begin{matrix}{M_{CUBIC} = \begin{bmatrix}P_{i} \\P_{j} \\P_{k}\end{bmatrix}} & (6)\end{matrix}$

FIG. 5 is a block diagram of another example 10B of the combinationextractor 10 of FIG. 1, including a position LUT 90.

The position LUT 90 outputs a corresponding position vector and acorresponding bias component among position vectors and bias componentsstored as data via output nodes OUT4 and OUT5, respectively, in responseto the first through n^(th) output color components that are input asaddresses via an input node IN4. In the case of FIG. 3, the position LUT90 outputs the position vector M_(CUBIC) of Equation 6 via the outputnode OUT4 and the bias component P_(k2) via the output node OUT5.

After operation 30, in operation 32, the coefficient generator 12 ofFIG. 1 generates a coefficient for representing the input color signalusing the input color signal having the first through m^(th) input colorcomponents input via an input node IN2, the combinations 13 extracted bythe combination extractor 10, and the bias component 15 input from thecombination extractor 10 and outputs the coefficient to the combinationselector 14.

Here, the first through m^(th) input color components input via theinput node IN2 may not be components on the intermediate color space.Thus, the apparatus of FIG. 1 may further include the color componentconverter 18 to convert the first through m^(th) input color componentsinto the components on the intermediate color space. Here, the firstthrough m^(th) input color components are converted into the componentson the intermediate color space in order to represent the combinations13 extracted by the combination extractor 10 as the components on theintermediate color space. In addition, only when input color componentsthe coefficient generator 12 uses to generate the coefficient must beequal to color components of the combinations extracted by thecombination extractor 10, the combination selector 14 can select desiredcombinations as described later.

The color component converter 18 of FIG. 1 converts the first throughm^(th) input color components of the input color signal input via theinput node IN2 into the components on the intermediate color space andoutputs the first through m^(th) input color components including thecomponents on the intermediate color space to the coefficient generator12. For example, when m=3, the first through third input colorcomponents are R, G, and B color components, and the intermediate colorspace is an LAB color space, the color component converter 18 convertsthe R, G, an B input color components into LAB input color componentsand outputs an input color signal having the LAB input color componentsto the coefficient generator 12. According to the present invention, forthis purpose, the color component converter 18 of FIG. 1 may be realizedas a component LUT 20. Here, the component LUT 20 stores the componentson the intermediate color space as data and outputs data correspondingto the first through m^(th) input color components of the input colorsignal, which are input as the addresses via the input node IN2, ascomponents of the input color signal to the coefficient generator 12.

In this case, the coefficient generator 12 generates the coefficientusing the input color signal having the converted color componentsoutput from the color component converter 18 and the combinations 13 andthe bias component 15 input from the combination extractor 10 andoutputs the coefficient to the combination selector 14.

FIG. 6 is a block diagram of an example 12A of the coefficient generator12 of FIG. 1, including a subtracter 100, an inverse number generator102, and a first multiplier 104.

The subtracter 100 subtracts the bias component 15 input from thecombination extractor 10 via an input node IN6 from the input colorsignal input via an input node IN5 and outputs the subtraction result tothe first multiplier 104.

Here, the inverse number generator 102 generates an inverse number ofthe position vector 13 input from the combination extractor 10 via aninput node IN7 and outputs the inverse number to the first multiplier104.

The first multiplier 104 multiplies the subtraction result of thesubtracter 100 by the inverse number generated by the inverse numbergenerator 102 and outputs the multiplication result as the coefficientto the combination selector 14 via an output node OUT6.

For example, in a case of FIG. 3, the coefficient generator 12A of FIG.6 generates a coefficient C_(color) as in Equation 7:C _(Color) =M _(CUBIC) ⁻¹·(C _(in) −P _(k2))  (7)wherein M_(CUBIC) ⁻¹ denotes the inverse number of the position vectorM_(CUBIC), C_(in) denotes the input color signal, and P_(k2) denotes thebias component. Here, Equation 7 can be derived from Equation 8:C _(in) =M _(CUBIC) ·C _(color) +P _(k2)  (8)wherein, when C_(color) is represented as in Equation 9, C_(in) can berepresented as in Equation 10 or 11:C_(color)=[αβγ]  (9)wherein α, β, and γ denote sizes of the position components P_(k),P_(i), and P_(j) of C_(in), respectively, as shown in FIG. 3.C _(in) =α·P _(k1)+(1−α)·P _(k2) +β·P _(i) +γ·P _(j)  (10)C _(in) =α·P _(k) +β·P _(i) +γ·P _(j) +P _(k2)  (11)

After operation 32, in operation 34, the combination selector 14 selectsdesired combinations among the extracted combinations input from thecombination extractor 10 using the coefficient generated by thecoefficient generator 12 and outputs the selected combinations to theoutput unit 16.

FIG. 7 is a block diagram of an example 14A of the combination selector14 of FIG. 1, including a coefficient clipping unit 120 and a secondmultiplier 122.

The coefficient clipping unit 120 of FIG. 7 selects only coefficientsbelonging to a specified range in which the input color signal can berepresented, among coefficients input from the coefficient generator 12via an input node IN8 and outputs the selected coefficients to thesecond multiplier 122. For example, the specified range may be between 0and 1. The second multiplier 122 multiplies the extracted combinationsrepresented in the position vectors input from the combination extractor10 via an input node IN9 by an output of the coefficient clipping unit120 and outputs the multiplication results as the selected combinationsto the output unit 16 via an output unit OUT7.

For example, when coefficients not belonging to the specified range inwhich the input color signal can be represented are input, thecoefficient clipping unit 120 of the combination selector 14A of FIG. 7outputs “0” to the second multiplier 122. Therefore, combinationscorresponding to the coefficients not belonging to the specified rangemay not be output via the second multiplier 122.

After operation 34, in operation 36, the output unit 16 generates theoutput color signal using the combinations selected by the combinationselector 14 and outputs the output color signal via an output node OUT1.Here, the output color signal can be represented as in Equation 12:

$\begin{matrix}{\sum\limits_{s = 1}^{n}{\delta_{s}P_{s}}} & (12)\end{matrix}$wherein P_(S) denotes each of the first through n^(th) output colorcomponents, and δ_(s) the size of P_(s).

FIG. 8 is a block diagram of an example 16A of the output unit 16 ofFIG. 1, including an adder 140, a first error generator 142, a firststorage 144,. and a signal selector 146.

The adder 140 adds the selected combinations input from the combinationselector 14 via an input node IN10 to the bias component 15 input fromthe combination extractor 10 via an input node IN11 and outputs theaddition result to each of the first error generator 142 and the firststorage 144.

Here, the first error generator 142 generates an error between theaddition result input from the adder 10 and the first through m^(th)input color components input via an input node IN12 and outputs theerror to the first storage 144.

The first storage 144 matches the addition result of the adder 140 withthe error generated by the first error generator 142 to accumulate andstore the addition result and the error. Here, the signal selector 146selects the smallest error among the errors stored in the first storage144, reads the addition result used for generating the selected smallesterror as the output color signal from the first storage 144, and outputsthe output color signal via an output node OUT8.

FIG. 9 is a block diagram of another example 16B of the output unit 16of FIG. 1, including an adder 160, a second error generator 162, asecond storage 164, an error extractor 166, and a first mean unit 168.

The adder 160 adds the selected combinations input from the combinationselector 14 via an input node IN13 to the bias component 15 input fromthe combination extractor 10 via an input node IN14 and outputs theaddition result to each of the second error generator 162 and the secondstorage 164.

The second error generator 162 generates an error between the additionresult of the adder 160 and the first through m^(th) input colorcomponents input via an input node IN15 and outputs the error to thesecond storage 164.

The second storage 164 matches the addition result of the adder 160 withthe error generated by the second error generator 162 to accumulate andstore the addition result and the error. Here, the error extractor 166extracts errors equal to or less than a specified value among the errorsaccumulated and stored in the second storage 164 and outputs theextracted errors to the first mean unit 168.

Here, the first mean unit 168 reads addition results corresponding tothe errors extracted by the error extractor 166 from the second storage164 and outputs a mean of the read addition results as the output colorsignal via an output node OUT9.

FIG. 10 is a block diagram of still another example 16 C of the outputunit 16 of FIG. 1, including an adder 180, a third storage 182, and asecond mean unit 184.

The adder 180 adds the selected combinations input from the combinationselector 14 via an input node IN16 to the bias component 15 input fromthe combination extractor 10 via an input node IN17 and outputs theaddition result to the third storage 182.

The third storage 182 accumulates and stores the addition result of theadder 180. Here, the second mean unit 184 outputs a mean of additionresults read from the third storage 182 as the output color signal viaan output node OUT10.

The output unit 16 of FIG. 1 may include only the adder 140, 160, or180. In this case, the adder 160 adds the selected combinations inputfrom the combination selector 14 to the bias component 15 input from thecombination extractor 10 and outputs the addition result as the outputcolor signal.

In a case where the color component converter 18 is included, the adder140, 160, or 180 of FIG. 8, 9, or 10 receives the first through m^(th)input color components from the color component converter 18. However,in a case where the color component converter 18 is not included, theadder 140, 160, or 180 receives the first through m^(th) input colorcomponents from the outside of the apparatus of FIG. 1.

A computer-readable storage medium storing a computer program forcontrolling an apparatus for converting a color signal, according to thepresent invention, will now be explained.

The computer-readable recording medium storing a computer programcontrols a color signal converter for converting an input color signalhaving first through m^(th) input color components into an output colorsignal having first through n^(th) output color components. For thispurpose, the computer program performs: extracting combinations of thefirst through n^(th) output color components; generating a coefficientfor representing the input color signal using the input color signal andthe extracted combinations; selecting desired combinations among theextracted combinations using the coefficient; and generating the outputcolor signal using the selected combinations.

In an apparatus and a method for converting a color signal, according tothe above-described embodiments of the present invention, and acomputer-readable recording medium for storing a computer program forcontrolling the apparatus, an input color signal can be correctlyrepresented without an error using a display device. Also, since allcombinations of representable output color components are considered, acolor gamut of the display device can be maximally used. In addition, aninput color signal having a limited number, m, of color components canbe easily converted into an output color signal having a larger number,n, of color components. Moreover, the output color signal can begenerated as described with reference to FIG. 8, 9, or 10. As a result,the discontinuation of color representation can prevent from beingoccurred during the representation of a neighboring color signal.

Although a few embodiments of the present invention have been shown anddescribed, the present invention is not limited to the describedembodiments. Instead, it would be appreciated by those skilled in theart that changes may be made to these embodiments without departing fromthe principles and spirit of the invention, the scope of which isdefined by the claims and their equivalents.

1. An apparatus for converting an input color signal comprising firstthrough m^(th) input color components into an output color signalcomprising first through n^(th) (n>m) output color components, theapparatus comprising: a combination extractor which extractscombinations for the first through n^(th) output color components; acoefficient generator which generates a coefficient for representing theinput color signal using the input color signal and the extractedcombinations; a combination selector which selects desired combinationsamong the extracted combinations using the coefficient; and an outputunit which generates the output color signal using the selectedcombinations.
 2. The apparatus of claim 1, further comprising: a colorcomponent converter which converts the first through m^(th) input colorcomponents of the input color signal into components on an intermediatecolor space, wherein the coefficient generator generates the coefficientusing the converted color components of the input color signal outputfrom the color component converter and the extracted combinations. 3.The apparatus of claim 2, wherein the color component convertercomprises a component lookup table which comprises the first throughm^(th) input color components of the input color signal as addresses andthe components on the intermediate color space as data.
 4. The apparatusof claim 1, wherein the combination extractor converts the extractedcombinations into position components for representing a position of aninternal space of a polyhedron on an intermediate color space and aposition vector comprising a bias component of the polyhedron on theintermediate color space, and outputs the converted result.
 5. Theapparatus of claim 4, wherein the combination extractor comprises: acombiner which extracts a possible combination of a specified number ofoutput color components among the first through n^(th) output colorcomponents and outputs the extracted combination; a component generatorwhich generates a position component comprising the bias component amongthe position components using the first through n^(th) output colorcomponents and the extracted combination; and a position vectorgenerator which generates the position vector using the extractedcombination and the generated position component, wherein the specifiednumber is less than a number of coordinate axes of the polyhedron and asfew as a number of the bias components.
 6. The apparatus of claim 4,wherein the combination extractor comprises a position lookup table(LUT) which comprises the first through n^(th) output color componentsas addresses and the position vector and the bias component as data. 7.The apparatus of claim 4, wherein the coefficient generator comprises: asubtracter which subtracts the bias component input from the combinationextractor from the input color signal; an inverse number generator whichgenerates an inverse number of the position vector; and a firstmultiplier which multiplies the subtraction result by the inverse numberof the position vector and outputs the multiplication result as thecoefficient.
 8. The apparatus of claim 4, wherein the combinationselector comprises: a coefficient clipping unit which selectivelyoutputs only coefficients belonging to a specified range in which theinput color signal is capable of being represented, among thecoefficients; and a second multiplier which multiplies the extractedcombinations represented by the position vector by an output of thecoefficient clipping unit and outputs the multiplication results as theselected combinations.
 9. The apparatus of claim 4, wherein the outputunit comprises an adder which adds the selected combinations to the biascomponent and outputs the addition result as the output color signal.10. The apparatus of claim 9, wherein the output unit further comprises:a first error generator which generates an error between the additionresult and the first through m^(th) input color components; a firststorage which matches the addition result with the error to accumulateand store the addition result and the error; and a signal selector whichselects the smallest error among the errors stored in the first storageand reads the addition result used for generating the selected error asthe output color signal from the first storage.
 11. The apparatus ofclaim 9, wherein the output unit further comprises: a second errorgenerator which generates an error between the addition result and thefirst through m^(th) input color components; a second storage whichmatches the addition result with the error to accumulate and store theaddition result and the error; an error extractor which extracts errorsequal to or less than a specified value among the errors stored in thesecond storage; and a first mean unit which reads the addition resultscorresponding to the extracted errors from the second storage andoutputs a mean of the addition results as the output color signal. 12.The apparatus of claim 9, wherein the output unit further comprises: athird storage which accumulates and stores the addition result; and asecond mean unit which outputs a mean of the addition results read fromthe third storage as the output color signal.
 13. The apparatus of claim5, wherein the extracted combinations are expressible by the followingequation:${n_{c} =_{\;}{{{}_{}^{}{}_{}^{}} = \frac{n!}{{\left( {n - Q} \right)!} \times {Q!}}}},$and wherein n_(c) denotes the number of extracted combinations, and Qdenotes the specified number.
 14. The apparatus of claim 5, wherein theposition component P_(k) expressible by the following equation:P _(k) =P _(k1) −P _(k2,) wherein bias components P_(k1), and P_(k2) areexpressible by the following equations: $\begin{matrix}{P_{k\; 1} = {\sum\limits_{s = 1}^{n}\left( {\sigma_{s}^{1} \cdot P_{s}} \right)}} \\{P_{k\; 2} = {\sum\limits_{s = 1}^{n}\left( {\sigma_{s}^{2} \cdot P_{s}} \right)}}\end{matrix},{and}$ wherein P_(s) denotes each of the first throughn^(th) output color components, and σ_(s) ¹ and σ_(s) ² are expressibleby the following equations: ${\sigma_{s}^{1} = \begin{Bmatrix}{{1\mspace{14mu} s} \in \left\{ {{s\text{|}{P_{s} \cdot \left( {P_{i} \times P_{j}} \right)}} < 0} \right\}} \\{0\mspace{14mu}{otherwise}}\end{Bmatrix}},{and}$ $\sigma_{s}^{1} = {\begin{Bmatrix}{{1\mspace{14mu} s} \in \left\{ {{s\text{|}{P_{s} \cdot \left( {P_{i} \times P_{j}} \right)}} > 0} \right\}} \\{0\mspace{14mu}{otherwise}}\end{Bmatrix}.}$
 15. The apparatus of claim 7, wherein the coefficientgenerator generates a coefficient C_(color) expressible by the followingequation:C _(color) =M _(CUBIC) ⁻¹·(C_(in) −P _(k2)), and wherein M_(CUBIC) ⁻¹denotes the inverse number of the position vector M_(CUBIC), C_(in)denotes the input color signal, and P_(k2) denotes the bias component.16. A method of converting an input color signal comprising firstthrough m^(th) input color components into an output color signalcomprising first through n^(th) (n>m) output color components, themethod comprising: extracting combinations for the first through n^(th)output color components; generating a coefficient for representing theinput color signal using the input color signal and the extractedcombinations; selecting desired combinations among the extractedcombinations using the coefficient; and generating the output colorsignal using the selected combinations.
 17. A computer-readablerecording medium storing processing instructions for causing a processorto perform a method of controlling an apparatus for converting an inputcolor signal comprising first through m^(th) input color components intoan output color signal comprising first through n^(th) (n>m) outputcolor components, the method comprising: extracting combinations of thefirst through n^(th) output color components; generating a coefficientfor representing the input color signal using the input color signal andthe extracted combinations; selecting desired combinations among theextracted combinations using the coefficient; and generating the outputcolor signal using the selected combinations.